ci: backwards compatibility test

WIP.

.github/workflows/backwards-compat.yml

@@ -0,0 +1,39 @@
+name: Backwards Compatibility Test
+
+on:
+  # tests must run for a PR to be valid and pass merge queue muster
+  # on main, we want to know that all commits are passing at a glance, any deviation should help bisecting errors
+  # the merge run checks should show on master and enable this clear test/passing history
+  merge_group:
+    branches: [main]
+  pull_request:
+    branches: ["*"]
+
+jobs:
+  backwards-compat:
+    runs-on: ubuntu-latest
+    steps:
+      - name: Checkout code
+        uses: actions/checkout@v4
+
+      - name: Install Rust
+        uses: dtolnay/rust-toolchain@stable
+
+      - uses: Swatinem/rust-cache@v2
+        continue-on-error: true
+
+      - name: Start a service-based local network
+        env:
+          SN_LOG: "all"
+        uses: jacderida/sn-local-testnet-action@backwards-compat-test
+        with:
+          action: start
+          build: true
+          interval: 2000
+          node-path: target/release/safenode
+          faucet-path: target/release/faucet
+          platform: ubuntu-latest
+          service: true
+          set-safe-peers: false
+          node-manager-branch: backwards-compat-test
+          node-manager-repo-owner: jacderida